Inspector Gadget was the first series of the Inspector Gadget franchise. It was created by DiC in alliance with Lexington Broadcast Services and Bohbot Entertainment. The series ran from 1983 to 1986, with a Christmas special airing in 1993.
- Inspector Gadget ― Voiced by Gary Owens in the original version of the pilot and by Don Adams in the re-dubbed version of the pilot and the rest of the series. He is the titular protagonist who is a cyborg detective with various gadgets built into his body, most activated by saying, "Go go Gadget" and then the name of the gadget he needs to use. He is a world-famous detective, but he's bumbling, gullible, and incompetent.
- Penny Brown ― Known as Sophie in the French version. Voiced by Mona Marshall in the pilot, Cree Summer in the rest of the first season, Holly Berger in the second season, and Erica Horn in Inspector Gadget Saves Christmas. She is the deuteragonist who is Gadget's niece and is equipped with a computer book with information on all of Claw's M.A.D. agents and a watch communicator she uses to keep in touch with Brain. Penny and Brain secretly aid Gadget on his missions because of his stupidity.
- Brain ― Known as Finot in the French version. Voiced by Frank Welker. He is the tritagonist who is Penny's intelligent and bipedal dog and often disguises himself to avoid being seen by Gadget. Unfortunately, this tends to backfire on him when Gadget mistakes him for a M.A.D. agent and then tries to arrest him. He communicates to Penny through his special dog collar and pantomime to explain what's happening to Gadget.
- Chief Quimby ― Known as Chief Gontier in the French version. Voiced by Dan Hennessey in the first season and Maurice LaMarche in the second season. He is the secondary tritagonist who appears in the beginning of each episode to give Gadget an exploding message that tells the Inspector about Claw's evil plan, Gadget casually throwing the message back at his face each time. He appears again at the end of each episode to congratulate Gadget for ruining Claw's scheme and arresting the M.A.D. agents.
- Dr. Claw ― Known as Docteur Gang in the French version. Voiced by Frank Welker and in some episodes by Don Francks. Claw is the main antagonist who is the unseen leader of an international criminal organization called M.A.D. All the audience ever sees of him are his black-sleeved arms and metallic-gloved hands. He speaks in a deep sinister voice and frequently plots to carry out an evil scheme and / or eliminate Inspector Gadget in each episode. He is assisted by legions of M.A.D. agents. Each episode ends with Claw's plan thwarted, the M.A.D. agents arrested, and Claw himself escaping and vowing to get Gadget next time. He owns a cat named M.A.D. Cat, whom he either pets or abuses, depending on his mood.
- M.A.D. Agents ― They are the secondary antagonists who work for Claw. The M.A.D. agents all wear either black jumpsuits with the word "MAD" on their chests or disguises related to the theme of the episode. In addition, many episodes featured a one-time M.A.D. agent with a name and a distinguishable modus operandi who gets arrested and never returns. The second season started a trend of M.A.D. agents reappearing in 3-episode story arcs without getting arrested.
- M.A.D. Cat ― Voiced by Frank Welker. He is the tertiary antagonist who is Claw's fat cat whom he often pets or pounds on. M.A.D. Cat always sits by Claw's computer as he watches his master gloat as he tries to stop Gadget.
- Corporal Capeman ― Voiced by Townsend Coleman. Capeman was introduced in season two as Gadget's even more incompetent sidekick. Capeman has a mutual hatred for Brain. He only appeared in 9 of the 21 Season 2 episodes.